Ahead of today's opening free practice session, the air temperature is 17 degrees C, while the track temperature is 22 degrees. Though a little overcast, the sun is breaking through in parts and currently there is certainly no sign of the rain that was forecast.

The lights go green and as ever the Force Indias lead the way. Sadly, and not for the first time this year, there is a problem with the timing screens.

One of the last out is David Coulthard, who is taking part in his last ever Formula One Grand Prix this weekend. To mark the occasion, his Red Bull sports a special 'Wings for Life' livery.

Race Control announces that it doesn't expect rain in the opening twenty-five minutes of the session, and that there is only a 20 percent chance of any rain falling during the session.

Sebastian Vettel is sporting a natty new helmet design. It features photographs of him and the team celebrating that famous victory at Monza.

Tyre options this weekend are medium and soft.

Twelve minutes into the session, Robert Kubica looks to be the first driver to post a time, the Pole looking to hold on to third in the championship. As it happens, at the end of his 'flying lap' he dives into the pits.

With McLaren running a new rear wing here, Ferrari is going to great lengths to hide the rear wing on Kimi Raikkonen's car as the Finn climbs in.

Twenty-two minutes into the session, Piquet is back on track, and looking likely to post the first time of the weekend. He crosses the line at 1:16.510 to post the benchmark.

As Bourdais posts 15.235, Rubens Barrichello is in the Honda garage talking to his father, who, naturally enough, looks like a slightly older version of the Brazilian driver.

Bourdais goes quickest, having improved to with a 13.839, the Frenchman keen to retain his seat for next season. In the Ferrari garage, Massa finally removes hit anorak and looks set to go out.

Bourdais, Vettel, Rosberg, Glock, Piquet, Trulli, Nakajima and Barrichello.

Thirty-six minutes into the session, Raikkonen leave the pits. However, it is fellow-Finn, Kovalainen who takes the top spot, crossing the line at 13.194. Glock goes second and Heidfeld third.

Forty minutes into the session, a huge cheer erupts from the grandstand opposite the pits as Massa heads down the pitlane. Elsewhere, however, Hamilton goes quickest in the first sector, and again in the second, eventually crossing the line at 12.731 to go quickest. McLaren 1-2.

As Hamilton goes quickest in the first two sectors of his next lap, Button goes fourth, ahead of Heidfeld, Bourdais and Webber. Hamilton posts 12.495.

Massa goes second with a 12.688, 0.193s off Hamilton's pace. Raikkonen has yet to post a time, as has Fisichella, Sutil, Kubica and Alonso.

At half-time, it's: Hamilton, Massa, Kovalainen, Webber, Heidfeld, Glock, Piquet, Button, Bourdais and Vettel.

A 12.557 sees Massa close to within 0.062s of his title rival, as a few spots of rain fall on the far side of the track. Race Control declares that it is now officially a wet session.

Kubica goes third with a 12.874 as Alonso comes out to play. In the Ferrari garage mechanics are working on Raikkonen's car, the 2007 World Champion now the only man to have not posted a time.

Alonso is one of several drivers to have run wide, however, though a very light drizzle falls from time to time the track is not 'wet', not by any real stretch of the imagination. The Spaniard goes seventh with a 13.443, 0.948s off Hamilton's time.

With just over half-an-hour remaining, Hamilton is back on track, as Raikkonen leaves the Ferrari garage.

The Ferrari driver goes tenth with a 13.557, but then spins in the Senna S. However, he is able to continue. There is clearly more moisture in the air, but the track still looks dry. Indeed, Massa improves to within 0.047s of Hamilton.

No sign of the soft option tyre yet, as the drivers stick with the medium option.

Piquet is warned that his crew can now see "a little bit of rain falling" on their TV screens.

Raikkonen goes quickest in the second sector, which is enough to see him go second, just 0.034s off Hamilton's pace and making it a Ferrari 2-3. Alonso, who had just improves to fifth, is demoted to sixth.